Patent document 1 describes an example of a seat reclining device that fixes a seatback to a seat cushion of a seat at a predetermined angle.
A seat reclining device includes a first bracket that is coupled to the seat cushion, a cam that is rotated relative to the first bracket, pawls moved in the radial direction of the first bracket by the rotation of the cam, and a second bracket that is coupled to the seatback and rotated relative to the first bracket. The rotation of the cam moves the pawls toward the outer side in the radial direction so that the outer teeth of each pawl engages with the inner teeth on the outer circumferential wall of the second bracket and restricts rotation of the second bracket. This keeps the rotation angle of the second bracket relative to the first bracket at a predetermined angle.
The seat reclining device described in patent document 1 includes a lock restriction mechanism that separates the outer teeth of each pawl from the inner teeth of the second bracket and keeps the outer teeth of each pawl disengaged from the inner teeth of the second bracket.
The lock restriction mechanism has the structure described below.
The second bracket has a central portion, which includes a recess, and an inner circumferential portion, which extends in the circumferential direction in the recess. Each pawl includes a first block and a second block that are arranged in different stages. The first block is located toward the radially outer side of the second block, and the radially outer end surface of the first block includes outer teeth. The radially outer end surface of the second block is configured to contact, when the pawls move toward the outer side in the radial direction, the inner circumferential portion of the second bracket before the outer teeth of the pawls engage the inner teeth of the second bracket. This structure restricts movement of the pawls in the radial direction and keeps the outer teeth of the pawls disengaged from the inner teeth of the second bracket.